Polarized Raman spectroscopy study of CVD-grown Cr 2 S 3 flakes: unambiguous identification of phonon modes.

We report a systematic Raman spectroscopy investigation of chemical vapor deposited 2D nonlayered Cr 2 S 3 , with both linearly and circularly polarized light over a wide temperature range (5-300 K). Temperature-dependent Raman spectra exhibit a good linear relationship between the peak positions of the phonon modes and temperature. Angle-resolved polarized Raman spectra reveal the polarization-dependent optical response of in-plane and out-of-plane phonon modes. Helicity-dependent Raman investigations complete definite assignment of all the phonon modes observed in the Raman spectra of 2D nonlayered Cr 2 S 3 by the optical selection rule based on a Raman tensor. Our work realizes clear phonon mode identification over a wide temperature range for the emerging material 2D Cr 2 S 3 , an important representative of nonlayered 2D system with unique properties for optoelectronic and spintronic applications.